Expansion dowel assembly

Abstract

An expansion dowel assembly is formed of an axially extending dowel body and an expansion member. The dowel body has a support surface inclined relative to the axis of the dowel body along which the expansion member can be displaced for anchoring the dowel assembly in an opening such as a borehole. At least a portion of the support surface is in the form of a groove extending in the axial direction of the dowel body and the bottom of the groove is inclined so that the expansion member is forced radially outwardly away from the axis of the dowel body as it is displaced through the groove.

I claim: 
     
       1. An exposure dowel assembly comprising an axially extending dowel body having a front and a rear end with the front end arranged to be inserted first into an opening into which the dowel assembly is to be inserted, and an axially extending expansion member having a front end and a rear end and arranged to be supported on said dowel body and to be displaced in the axial direction of the dowel body away from the rear end of said dowel body for anchoring said dowel body in the opening, said dowel body having engagement means adjacent the rear end thereof for applying axially directed forces to said dowel body, said dowel body having an axially extending support surface for said expansion member extending from a location intermediate the front and rear ends of said dowel body toward the front end and inclined at an angle to the axis of said dowel body, said dowel body and expansion member being engageable with one another to form an axially extending cylindrically shaped outer peripheral surface so that the dowel assembly can be inserted into a corresponding cylindrically shaped opening prior to being expanded, wherein the improvement comprises that said support surface is formed at least in part by a centrally arranged groove extending inwardly into and in the axial direction of said dowel body from the location intermediate the front and rear ends of said dowel body toward the front end thereof and the bottom of said groove being inclined relative to the axis of said dowel body for displacing said expansion member radially outwardly from the axis of said dowel body as said expansion member is displaced along said groove in the direction toward the front end of the dowel body, said groove having oppositely disposed side walls extending upwardly from the bottom of said groove and said side walls decreasing in height from the intermediate location to the front end of said dowel body, and said expansion member is shaped to fit into said groove in said dowel body in contact with said side walls in said groove and with said bottom and in the insertion condition of said expansion dowel assembly the front ends of said dowel body and expansion member are arranged transversely of the axis of said dowel body and the lateral outer surfaces of said dowel body and expansion member in the insertion condition form a continuous cylindrical surface. 
     
     
       2. An expansion dowel assembly as set forth in claim 1, wherein said groove is U-shaped in cross-section transverse to the axial direction of said dowel body. 
     
     
       3. An expansion dowel assembly as set forth in claim 1 or 2, wherein the bottom of said groove is arc-shaped in transverse section. 
     
     
       4. An expansion dowel assembly as set forth in claim 3, wherein the width of said groove is in the range of 0.3 to 0.7 times the outside diameter of said dowel body. 
     
     
       5. An expansion dowel assembly as set forth in claim 4, wherein the width of said groove is 0.5 times the outside diameter of said dowel body. 
     
     
       6. An expansion dowel assembly, as set forth in claim 1, wherein said groove is V-shaped in cross-section transversely of the axis of said dowel body. 
     
     
       7. An expansion dowel assembly, as set forth in claim 6, wherein said groove has a pair of angularly spaced side surfaces with the angular spacing of said side surfaces being in the range of 90° to 120°. 
     
     
       8. An expansion dowel assembly comprising an axially extending dowel body having a front end and a rear end with the rear end arranged to be inserted first into an opening into which the dowel assembly is to be inserted, and an axially extending expansion member having a front end and a rear end and arranged to be supported on said dowel body and to be displaced in the axial direction of the dowel body away from the rear end of said dowel body for anchoring said dowel body in the opening, said dowel body having engagement means adjacent the rear end thereof for applying axially directed forces to said dowel body, said dowel body having an axially extending support surface for said expansion member extending from a location intermediate the front and rear ends of said dowel body toward the front end and inclined at an angle to the axis of said dowel body, said dowel body and expansion member being engageable with one another to form an axially extending cylindrically shaped outer peripheral surface so that the dowel assembly can be inserted into a corresponding cylindrically shaped opening prior to being expanded, wherein the improvement comprises that said support surface is formed at least in part by a centrally arranged groove having oppositely disposed side walls, which groove extending inwardly into and in the axial direction of said dowel body from the location intermediate the front and rear ends of said dowel body toward the front end thereof and the bottom of said groove being inclined relative to the axis of said dowel body for displacing said expansion member radially outwardly from the axis of said dowel body as said expansion member is displaced along said groove in the direction toward the front end of said dowel body, and said expansion member is shaped to fit into said groove in said dowel body and in the insertion condition of said expansion dowel assembly the front ends of said dowel body and expansion member are arranged transversely of the axis of said dowel body and the lateral outer surfaces of said dowel body and expansion member in the insertion condition form a continuous cylindrical surface, said groove is U-shaped in cross-section transverse to the axial direction of said dowel body, the bottom of said groove is arc-shaped in transverse section, and the side walls of said groove extending upwardly from said bottom thereof decrease in height from the intermediate location toward the front end of said dowel body. 
     
     
       9. An expansion dowel assembly as set forth in claim 8, wherein the inwardly facing surfaces of said side walls of said groove extending upwardly from said bottom thereof are disposed in parallel relation. 
     
     
       10. An expansion dowel assembly, as set forth in claim 8, wherein said expansion member has a pair of laterally spaced side surfaces having increasing width from the rear end toward the front end of said expansion element and a ridge extending between said side surfaces and projecting outwardly from said side surfaces and having a configuration complementary to said groove in said dowel body. 
     
     
       11. An expansion dowel assembly comprising an axially extending dowel body having a front end and a rear end with the front end arranged to be inserted first into an opening into which the dowel assembly is to be inserted, and an axially extending expansion member having a front end and a rear end and arranged to be supported on said dowel body and to be displaced in the axial direction of said dowel body away from the rear end of said dowel body for anchoring said dowel body in the opening, said dowel body having engagement means adjacent the rear end thereof for applying axially directed forces to said dowel body, said dowel body having an axially extending support surface for said expansion member extending from a location intermediate the front and rear ends of said dowel body toward the front end and inclined at an angle to the axis of said dowel body, said dowel body and expansion member being engageable with one another to form an axially extending cylindrically shaped outer peripheral surface so that the dowel assembly can be inserted into a corresponding cylindrically shaped opening prior to being expanded, wherein the improvement comprises that said support surface is formed at least in part by a centrally arranged groove extending inwardly into and in the axial direction of said dowel body from the location intermediate the front and rear ends of said dowel body toward the front end thereof and the bottom of said groove being inclined relative to the axis of said dowel body for displacing said expansion member radially outwardly from the axis of said dowel body as said expansion member is displaced along said groove in the direction toward the front end of said dowel body, and said expansion member is shaped to fit into said groove in said dowel body and in the insertion condition of said expansion dowel assembly the front ends of said dowel body and expansion member are arranged transversely of the axis of said dowel body and the lateral outer surfaces of said dowel body and expansion member in the insertion condition form a continuous cylindrical surface, and said dowel body has an axially extending slot extending from the base of said groove to the outside surface of said dowel body.